Feng Liu and Katsunori Wakabayashi,
Photonic Weyl semimetals in two-dimensional dielectric arrays,
Jpn. J. Appl. Phys. 58 SDDD01 (2019).
doi: 10.7567/1347-4065/ab088b

Abstract: Weyl semimetal (WSM) is a novel topological phase of matter that broadens classifications of topological solid-state materials beyond insulators. WSM features robust surface states that connect pairs of Weyl nodes with opposite topological charges in momentum space. In this work, we show that in a dielectric photonic crystal on a square lattice, topological edge states appear owing to nontrivial topological charges of degenerate px and py electromagnetic modes in momentum space, which is similar to WSM. Our results serve to design topological semimetal states in bosonic systems without breaking any symmetry.